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Original question:

TDP142: Asking for TDP142 spec about eDP

TDP142: Some application problem need help

Gabriel Wang1
Genius 4715 points
Part Number: TDP142

Dear Expert

Our company uses FPGA+TDP142 to output DP video signals. I would like to inquire about some issues with the TDP142 chip. Thank you! The problem is as follows
1: AUX auxiliary communication signal AUX_ P and AUX_ Is N a pair of differential signals? How does it communicate with the display device. Chapter "9.2.1" of the TDP142 specification book discusses how FPGA communicates with TDP142 through AC coupling with FPGA?
2: Keep only DP_ Is it possible to disable AUX and SNOOPENZ with the HPDIN hot swap feature? AUX_ P-connected pull-down resistor, AUX_ N is connected to Pull-up resistor, and SNOOPENZ is suspended.
3: TDP142 has two communication modes: GPIO and I2C. Is communication necessary? Equalization can be controlled by external hardware and does not require sniffing function.
4: Does TDP142 not require sniffing function mean that the chip is running at full power? After checking HPDIN, output a video signal.

  • 0
    TI__Guru**** 177011 points

    Hi,

    Please see my inserted response,

    1: AUX auxiliary communication signal AUX_ P and AUX_ Is N a pair of differential signals? How does it communicate with the display device. Chapter "9.2.1" of the TDP142 specification book discusses how FPGA communicates with TDP142 through AC coupling with FPGA?

    The AUX_CH is a half-duplex, bidirectional channel consisting of one differential pair. The AUX is communicated between the FPGA and the device while TDP142 snoops the communication when AUX snooping is enabled.


    2: Keep only DP_ Is it possible to disable AUX and SNOOPENZ with the HPDIN hot swap feature? AUX_ P-connected pull-down resistor, AUX_ N is connected to Pull-up resistor, and SNOOPENZ is suspended.

    No. When HPDIN is low, TDP142 is placed in low power mode. Disable AUX can only be done by the SNOOPENZ pin when in GPIO mode.


    3: TDP142 has two communication modes: GPIO and I2C. Is communication necessary? Equalization can be controlled by external hardware and does not require sniffing function.

    In GPIO mode, the DPEN pin controls whether DisplayPort is enabled, SNOOPENZ pin controls whether AUX snoop mode is enabled, and DPEQ pin provides the compensation for the TDP142 input channel loss. These pins are sampled at the TDP142 power-up.

    In I2C mode, you have to program the TDP142 registers first to achieve the same functionality. 


    4: Does TDP142 not require sniffing function mean that the chip is running at full power? After checking HPDIN, output a video signal.

    Correct. Once AUX snoop is disabled, management of TDP142 DisplayPort lanes are controlled through various configuration registers when in I2C mode. When TDP142 is enabled for GPIO mode (I2C_EN = "0"), the SNOOPENZ pin can be used to disable AUX snooping. When SNOOPENZ pin is high, the AUX snooping functionality is disabled and all four DisplayPort lanes will be active.

    Thanks

    David